---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Thu 02/10/22: 8 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:51 AM - Re: PWM ELEVATOR TRIM SERVO SPEED CONTROL (Robert L. Nuckolls, III) 2. 06:46 AM - Re: ground power deep discharge of battery (user9253) 3. 07:12 AM - Re: PWM ELEVATOR TRIM SERVO SPEED CONTROL (user9253) 4. 07:21 AM - Schematics (Neal George) 5. 08:48 AM - Re: Schematics (Bob Verwey) 6. 10:10 AM - Re: Re: ground power deep discharge of battery (Robert L. Nuckolls, III) 7. 10:11 AM - Re: Re: PWM ELEVATOR TRIM SERVO SPEED CONTROL (Robert L. Nuckolls, III) 8. 06:25 PM - Re: Schematics (user9253) ________________________________ Message 1 _____________________________________ Time: 05:51:50 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: PWM ELEVATOR TRIM SERVO SPEED CONTROL > ACTIVE voltage regulators incorporated as > suggested in the drawing are CONSTANT > VOLTAGE sources irrespective of load. > Motors do not automatically 'draw more > current' as their driving voltage is reduced. > Using a series resistor to control speed > makes speed regulation so poor that it SEEMS > as if motor current is being modulated with > speed . . . not so. I've had some direct questions on this topic . . . perhaps I went too far into the weeds with the physics and offered insufficient practical approach to individual solutions. If anyone is having trouble managing their trim system performance, please have them join us here on the List or drop me a line personally. I've worked trim systems on everything from C182 to Hawker 4000 and most of those in between. There ARE proven solutions but they may require tailoring to a builder's specific situation. It CAN be fixed. Bob . . . Un impeachable logic: George Carlin asked, "If black boxes survive crashes, why don't they make the whole airplane out of that stuff?" ________________________________ Message 2 _____________________________________ Time: 06:46:25 AM PST US Subject: AeroElectric-List: Re: ground power deep discharge of battery From: "user9253" With my circuit, both the master switch must be on and the momentary switch pushed in order to energize the ground power contactor. Installing an indicator light would be easier, but the light could be overlooked. Regardless, a fuse should be installed in series with the contactor coil to protect against reverse polarity. There is a 50-50 chance of the ground power battery being connected backwards. If the polarity is backwards, the diode that is across the contactor coil will conduct a large current and blow the fuse that you are going to install. Hopefully that will happen quick enough to prevent damage to expensive avionics. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=505967#505967 ________________________________ Message 3 _____________________________________ Time: 07:12:10 AM PST US Subject: AeroElectric-List: Re: PWM ELEVATOR TRIM SERVO SPEED CONTROL From: "user9253" Bob, thanks for the information. If I ever redesign my trim circuit, it will contain a LM317. You asked about the RV-12 trim circuit. Attached is a schematic of the original trim circuit. Van's has completely changed it in later models. But they still use PWM. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=505968#505968 Attachments: http://forums.matronics.com//files/trim_speed_738.png ________________________________ Message 4 _____________________________________ Time: 07:21:42 AM PST US Subject: AeroElectric-List: Schematics From: Neal George Gentlemen =93 I would like recommendations for a low-cost schematic drawing utility for s omeone who doesn=99t speak CAD... Neal George ________________________________ Message 5 _____________________________________ Time: 08:48:51 AM PST US From: Bob Verwey Subject: Re: AeroElectric-List: Schematics NANOCAD freeware On Thu, 10 Feb 2022, 17:26 Neal George, wrote: > Gentlemen =93 > > I would like recommendations for a low-cost schematic drawing utility for > someone who doesn=99t speak CAD... > > > Neal George > ________________________________ Message 6 _____________________________________ Time: 10:10:08 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: ground power deep discharge of battery >If the polarity is backwards, the diode that is across the contactor >coil will conduct a large current and blow the fuse that you are >going to install. >Hopefully that will happen quick enough to prevent damage to >expensive avionics. Nothing 'hopeful' about it. The diode, being FORWARD biased, will not have a voltage drop not exceeding 1 volt or so while the fuse is in the process of melting it's brains out . . . a couple milliseconds. The voltage impressed on the contactor coil during this interval is too short and too low for the contactor to even think about closing. Bob . . . Un impeachable logic: George Carlin asked, "If black boxes survive crashes, why don't they make the whole airplane out of that stuff?" ________________________________ Message 7 _____________________________________ Time: 10:11:31 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: PWM ELEVATOR TRIM SERVO SPEED CONTROL At 09:11 AM 2/10/2022, you wrote: > >Bob, thanks for the information. If I ever redesign my trim >circuit, it will contain a LM317. >You asked about the RV-12 trim circuit. Attached is a schematic of >the original trim circuit. >Van's has completely changed it in later models. But they still use PWM. PWM is much better than a simple series resistor but still far short of optimal performance possible with fewer components. Bob . . . Un impeachable logic: George Carlin asked, "If black boxes survive crashes, why don't they make the whole airplane out of that stuff?" ________________________________ Message 8 _____________________________________ Time: 06:25:23 PM PST US Subject: AeroElectric-List: Re: Schematics From: "user9253" I use ExpressPCB Classic. https://www.expresspcb.com/expresspcb-classic-pcb-layout-software/#wow-modal-id-1 The program is free and easy to learn. I used it to draw the schematics attached to my recent posts. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=505983#505983 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.